540 
W. L. WILLIAMS. 
practical medicine giving new insight into many of those peculiar 
epizootics, as well as to a large number of extraordinary cases 
of common affections, which at times so baffle and worry the 
practitioner. The extraordinary case in one locality, under one 
class of conditions, frequently constitutes the ordinary disease 
under wholly different surroundings. 
The study enlightens us to as to the etiology of many dis¬ 
eases since we not infrequently find the prevalence of a disease 
in a certain locality attributed to certain well marked local en¬ 
vironment ; when, in fact, the same disease and of like character 
exists in regions where the supposed essential etiological factor 
of the former locality is wholly absent. So it is that we find 
our writers attributing a disease at times to some local cause, 
when a more general knowledge of the distribution of the dis¬ 
ease would show them that it existed under conditions requiring 
some other explanation for its prevalence than that given. 
Again, we find our writers describing symptoms of a disease 
as those characteristic of a malady, when in reality they are 
overlooking the essential characters and are portraying vividly 
what they have seen in a limited area, perhaps in the compass 
of a few square miles in a great city. 
These omissions and errors find their way naturally into the 
class rooms of our veterinary colleges, and result in sending 
forth licentiates poorly equipped for such work as will fall to the 
lot of many in their chosen locations. 
Neither the time nor the data at hand will permit an exhaus¬ 
tive consideration of the subject before us, and the sole justifica¬ 
tion for presenting it is the hope of awakening an interest in 
this very important and instructive study. 
It was not deemed desirable to undertake the consideration 
of a great number of diseases, but rather of a few important 
affections which are more or less prevalent in the United States, 
which it is believed will serve as a ground work for an interest¬ 
ing discussion. 
In order to secure as complete date as possible in the brief 
time at my disposal, letters were addressed to about one hun- 
